Stiff aqueous explosive composition containing gilsonite

ABSTRACT

A stiff or highly viscous explosive composition of high sensitivity to detonation is made up of a mixture of 40 to 60 parts by weight, based on total composition, of ammonium nitrate and 15 to 35 parts of sodium nitrate at least partly dissolved in 8 to 15 parts of water, preferably including 1.5 to 5 parts of gilsonite as a carbonaceous fuel and sensitizer, 2 to 4 parts of paint grade fine flaked aluminum as a primary sensitizer and 0.3 to 4 parts of guar gum, preferably crosslinked, as a thickener or viscosity increasing agent. Sulfur is preferably included as a supplemental fuel and sensitizer. The slurry is plastic but preferably stiff enough to package in sticks analogous to dynamite.

United States Patent Cook et al. 1 1 Jan. 30, 1973 [W STlFF AQUEOUSEXPLOSIVE 3,238,074 3/1966 Griffith et 1. ..149 41 x COMPOSITIONCONTAINING 3,369.945 2/1968 Craig et al. ..149 41 x 3,473,983 10/1969Cook et al. 149 41 GILSONITE 3,507,718 4/1970 Mortensen et al ..l49/73 X[75] Inventors: Melvin Alonzo Cook; Donald T. Bailey, both of Salt LakeCity, Utah [73] Assignee: Ireco Chemicals, Salt Lake City,

Utah

[22] Filed: Feb. 22,1971

211 Appl. No.2 117,746

Related US. Application Data [63] Continuation-impart of Ser. No.497,442, Oct. 18,

1965, abandoned.

[521 U.S.(l ..l49/2, 149/21, 149/41 151 Int. Cl. ..Cll6b l/04 |51l|Field of Search ..l49/4l 44, 61), 21,73, 2. 149/112 |5o| ReferencesCited UNl'llil) STATES PATENTS 31183,] 27 3/1963 (iril'lilh ct al..l49/4l X Primary ExaminerStephen J. Lechert, Jr. Attorney-Edwin M.Thomas [57] ABSTRACT A stiff or highly viscous explosive composition ofhigh sensitivity to detonation is made up of a mixture of 40 to 60 partsby weight, based on total composition, of ammonium nitrate and 15 to 35parts of sodium nitrate at least partly dissolved in 8 to 15 parts ofwater, preferably including 1.5 to 5 parts of gilsonite as acarbonaceous fuel and sensitizer, 2 to 4 parts of paint grade fineflaked aluminum as a primary sensitizer and 0.3 to 4 parts of guar gum,preferably erosslinked, as a thickener or viscosity increasing agent.Sulfur is preferably included as a supplemental fuel and sensitizer. Theslurry is plastic but preferably still enough to package in sticksanalogous to dynamite.

3 Claims, No Drawings STIFF AQUEOUS EXPLOSIVE COMPOSITION CONTAININGGILSONITE This application is a continuation-in-part of Application,Ser. No. 497,442, filed Oct. 18, 1965, now abandoned.

BACKGROUND AND PRIOR ART Aluminum has long been known and used as animportant strength enhancing ingredient in many explosives for militaryand commercial uses. The increased strength resulting from the use ofaluminum in explosives is the result of the highly exothermal reactionwhere refers to oxygen derived in one way or another from the explosive.So strongly exothermal is this reaction that aluminum is found toincrease the strength even of strongly oxygen-negative conventionalexplosives. For example, 80/20 tritonal (80 percenttrinitrotoluenepercent aluminum) is appreciably stronger thantrinitrotoluene itself, despite the fact that the addition of aluminumto trinitrotoluene renders the oxygen balance considerably more negativethan for pure trinitrotoluene. Since the presence of aluminum in suchexplosives actually takes oxygen ordinarily in the products ofdetonation, in such components as carbon dioxide and water, theformation of which produces most of the heat of explosion in ammoniumnitrate-fuel explosives, there is the possibility that a balanced(50/50) aluminumwater mixture might itself be explosive underappropriate conditions. Thus, the reaction generates a heat of 1 .76Kcal./g. Also the reaction generates 2.1K cal./g. These heats are abouttwice the heat of explosion of average dynamites and low densitytrinitrotoluene.

For may years water-soluble, inorganic, oxygen-supplying salts such asnitrates, chlorates, and perchlorates have been used in explosivecompositions. Ammonium nitrate and sodium nitrate, in particular, findextensive use in commercial high explosives and blasting agents. Ofnecessity, such explosives often are stored under conditions of highrelative humidity and are used under wet conditions. The hygroscopicityand water-solubility of the inorganic oxygen-supplying salts areundesirable characteristics which may lead to deterioration of theexplosive compositions and to failures in use.

As described above, efforts have usually been made to exclude water fromexplosive compositions, or at least to minimize the amount of waterwhich enters the compositions. More recently, however, as in U.S. Pat.No. Re. 25,695, the presence of substantial amounts of water has beenrecognized as being beneficial in certain explosives rich in ammoniumnitrate and containing suitable amounts of a strong sensitizer such asaluminum. Most prior art compositions detonate satisfactorily only incolumns of relatively large cross-section and, additionally, require theuse of high explosive boosters to insure effective priming.

The instant invention provides a thickened, viscous, water-bearing,blasting explosive composition capable of propagating a detonation incolumns having very small diameters and in the absence of substantialconfinement, said explosive composition comprising at least 45 percentby weight of oxygen supplying salts, a large part of saidoxygen-supplying salts being ammonium nitrate and the balance being anoxygen-supplying salt selected from the group consisting of alkali anda1- kaline earth metal nitrates, ammonium perchlorate, and alkali andalkaline earth metal perchlorates, the total amount of oxygen-supplyingsalts in the composition being such as to provide an oxygen-balance ofbetween +10 and 10 percent; a thickener consisting of from about 0.5 toabout 4 percent by weight of water-dispersible thickening agent, such asguar gum; from about 2 to about 20 percent by weight of a supplementalnon-explosive fuel consisting essentially of carbonaceous material towhich sulfur may be added; and about 1 to about 4 percent by weight offine flaked paint grade aluminum powder as a primary fuel andsensitizer; all solid components of said explosive composition beinguniformly dispersed in the thickened mass, the liquid phase of which isa substantially saturated aqueous solution of said oxygen-supplyingsalts, the water in the composition representing from about 10 to about15 percent of the total weight of the composition, said explosivecomposition being free of selfexplosive ingredients and having a densityof at least 1.0 gram per cubic centimeter.

The nature of the present invention will become more apparent from thenon-limiting examples below which also illustrate the manner in whichimprovedexplosive compositions of the present invention can be made.Unless otherwise indicated, all parts are by weight.

It was found that sensitivity was improved, and also that density of theslurry was reduced by adding ground or powdered gilsonite. Thiscarbonaceous material has good fuel and sensitizing value. Sulfur wasadded in some cases and is often preferred as an additional fuel andsensitizer. It is particularly effective when sodium nitrate is used inthe oxidizer.

A series of experiments were performed as listed in the following table.In some of these, ethylene glycol was used to lower the freezing pointand also to add fuel value, since it contains carbon and hydrogen.

TABLE I Mix No. 1-120 1-121 1-122a 1108 AN- 57.3 57.3 40 Eth. Glycol 3.03.0 4 11,0 14 10.0 8.0 9.6 SN 15 15.0 15.0 35 S 5 5.5 3.5 7 Gilsonite 51.5 1.5 Fe? 5.0 5.0 A1. 4 4.0 4.0 2.0 NJ 0.3 0.3 0.3 Gum 0.4 0.4 0.4 0.3Renex"'" 0.5 0.15 0.15 Borax 0.015 Ox. Bal. l.92 0.3 0.30 Density 1.191.3 1.23 Dentonator Cap Cap ICB Cap Booster Results 40C very good D-45CD-45C D1.5C

with 25C border- D-17C very good 1X1 booster line P 5.2 6.0 Remarks= Lowdensity Borax due to gilsonite Cross-link It was found, in attempts touse more paint grade aluminum, that percent paint grade aluminumsmothered the mix, its volume Being too great for obtaining asatisfactory slurry consistency. With a composition containing only 1percent aluminum (Mix 1-- l l 1 detonation was obtained at 37 C. in a 1X 12 inch cylinder, using a l X 1 pentolite booster. This samplecontained no dry carbonaceous fuel to supplement the aluminum, but didcontain 4 percent ethylene glycol and some sulfur-also 3 percent ofcoarse aluminum, grade 101. A similar composition (Mix l-l 12), exceptthat it contained 2 percent of the fine paint grade aluminum and 2percent coarse aluminum, detonated at 6 C., using a similar booster,whereas the 1 percent paint grade mix failed with a larger 1C booster at2 C. Each of these contained 40 percent by weight, based on totalcomposition of ammonium nitrate, 4 percent ethylene glycol, 8 percentwater, 35 percent sodium nitrate, and 7 percent sulfur. Each containedalso 0.3 percent of guar gum as a thickener. Mix 1-111 had a density of1.44, whereas Mix No. l-l12 had density 1.3. Addition of the fine paintgrade aluminum lowers the density. Another Mix 1-1 10, similar to thetwo just described, but containing 4 percent fine or paint gradealuminum (Albron Powder), and no coarse aluminum, had a density at 38 C.of 1.31. A 1 X 12 tube filled with this slurry detonated very well witha l X l Pentolite booster at 38 C. The same mix detonated with a 1Cbooster at -4 C. in the same diameter. It was concluded that the latterhad a critical diameter less than or about equal to 1 inch at 5 C.

Mixes of the character of the three just described are stiff, viscousslurries. They can be poured at ordinary temperatures where they flowfreely though slowly. The viscosity of the gel or slurry can beincreased by adding more thickener or decreased by adding more waterand/or by adding ethylene glycol. Other water extenders, preferablythose having fuel value, such as glycols, glycerines, lower monohydricalcohols, and related nitrogeneous materials such as the watercompatible amides may be used. In some cases, amines may be used.Formamide was tried and found satisfactory as a liquid fuel and liquidextender.

Where cap sensitivity, or increased sensitivity, is desirable,additional quantities of finely divided carbonaceous material, orsoluble carbonaceous material such as gilsonite, may be used, inaddition to the starch or gum type thickeners, which are needed both forincreasing viscosity and for fuel value. The thickeners preferredordinarily are carbonaceous gums such as guar gum, locust-bean gum, butflours, starches, and gelling agents or colloidal or colloid formingmaterials in general, may be used. Their use in such compositions iswell known, being described in the older solid type explosive gels, forexample, in U.S. Pat. No. 2,847,291, and also in slurry type or pourablegel explosives. Water compatible celluloses, e.g., sodium carboxy methylcellulose also may be used. The efficiency of these thickeners for theirthickening function is, of course, increased by crosslinking, e.g., byuse of borax in small proportions. Proportions of gum or thickener maybe as low as 0.25 percent of the total weight of the slurry or gel, andas high as 4 percent or even more,

especially for the less efficient thickeners.

In the examples above, the paint grade aluminum generally had a particlesize less than 325 mesh.

In general, these thickened gels or slurries are improvements over theslurries invented by Cook and Farnam and described, for example, in U.S.Pat. No. 3,121,036, its Re. No. 25,695, and also in U.S. Pat. No.3,113,059. As described in U.S. Pat. No. 3,096,223, chlorates andperchlorates, especially ammonium perchlorate, may be used, substitutingthem for the sodium nitrate and even for part or all of the ammoniumnitrate described above, in some cases. Generally, it is preferred touse ammonium nitrate as the principal oxidizer, with minor quantities,relatively speaking of sodium nitrate and/or the inorganic chloratesand/or perchlorates. Other modifications will suggest themselves tothose skilled in the art.

What is claimed is:

l. A stiff, viscous aqueous explosive slurry composition suitable forpackaging and use in sticks, which comprises 40 to 60 parts by weight,based on the total composition, of ammonium nitrate, 15 to 35 parts ofsodium nitrate, 8 to 15 parts of water, 2 to 4 parts of fine flakedaluminum powder as a primary sensitizer, 1.5 to 5 parts of gilsonite asa carbonaceous fuel and sensitizer, up to 7 parts of sulfur as asupplemental fuel and sensitizer, and 0.3 to 4 parts of a waterdispersible thickening agent, said composition being free ofselfexplosive ingredients, having a bulk density of at least 1.0 gramsper cc., and being detonable by a standard blasting cap at ordinarytemperatures in diameters as small as 1 i ainches.

2. Composition according to claim 1 which contains no more than 10 partsby weight of water and contains 3 to 4 parts of ethylene glycol and issensitive to detonation by an ordinary blasting cap.

3. Composition according to claim 1 which contains 14 percent water, 15percent sodium nitrate, 5 percent sulfur, 5 percent gilsonite, and iscap-sensitive in a stick form.

1. A stiff, viscous aqueous explosive slurry composition suitable forpackaging and use in sticks, which comprises 40 to 60 parts by weight,based on the total composition, of ammonium nitrate, 15 to 35 parts ofsodium nitrate, 8 to 15 parts of water, 2 to 4 parts of fine flakedaluminum powder as a primary sensitizer, 1.5 to 5 parts of gilsonite asa carbonaceous fuel and sensitizer, up to 7 parts of sulfur as asupplemental fuel and sensitizer, and 0.3 to 4 parts of a waterdispersible thickening agent, said composition being free ofself-explosive ingredients, having a bulk density of at least 1.0 gramsper cc., and being detonable by a standard blasting cap at ordinarytemperatures in diameters as small as 1 1/4 inches.
 2. Compositionaccording to claim 1 which contains no more than 10 parts by weight ofwater and contains 3 to 4 parts of ethylene glycol and is sensitive todetonation by an ordinary blasting cap.